Head Salad

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

The oldest, most popular, most undemanding valuable green vegetable is salad

Among green vegetables, salad is of great value to humans. The history of its culture goes back to the distant past. It was already known in antiquity to the Greeks, Romans and Egyptians. In European countries, salad appeared in culture in the middle of the 16th century.

Until now, the origin of the cultivated forms of lettuce has not been precisely established, nor has its existing variety been established. The emergence of a huge number of lettuce varieties is the result of crossing between the main varieties that come from different countries. In Italy and neighboring countries, Romaine lettuce is widely cultivated. In the countries of central and northern Europe, varieties with oily leaves are common.

In America, varieties with crispy juicy leaves have become widespread, and, in particular, the Great Lakes salad, the heads of which reach a weight of 1 kg and are distinguished by their density. In China, Japan, Mongolia, asparagus salads are cultivated, in which, along with leaves, thick fleshy stems are used for nutrition. This valuable variety of salad is still a rarity. A large number of varieties belong to separate varieties, and also have a hybrid origin.

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The valuable nutritional and healing properties of lettuce have long been known. It is consumed mainly raw. It increases appetite and improves digestion. Lettuce plants grown in hot, dry weather sometimes have a bitter taste, which is due to the glucoside lactucion they contain. This substance has a calming effect, improves sleep and lowers high blood pressure. The salad is rich in vitamins B1, B2, E, C, carotene, potassium, calcium and iron salts. By the content of calcium salts, it ranks first among vegetables. In terms of the total salt content, salad is second only to spinach. It is also rich in microelements: it contains copper, zinc, cobalt, manganese, molybdenum, titanium, boron, iodine.

The cellular juice of the lettuce contains nitric acid, sulfuric acid and hydrochloric acid potassium salts, which have a beneficial effect on the activity of the kidneys, liver, pancreas and the circulatory system.

Lettuce is an annual herbaceous vegetable from the Asteraceae family. Its root is pivotal with numerous lateral branches located in the topsoil at a depth of 24-30 cm. Leaves are sessile, almost horizontal, of various shapes. The stem reaches 1-1.5 m in height, it is thin in leafy and head forms and thickened in asparagus lettuce. Inflorescences - a basket, one inflorescence contains 10-25 bisexual yellow flowers.

Lettuce is a self-pollinating plant, but cross-pollination by insects is also possible. The fruit is achene. The seeds are silvery gray, brown, yellow or black. When stored under normal conditions, their germination is maintained for 4 years.

Lettuce varieties belong to five varieties:

• leaf lettuce, forming a plant with a rosette of leaves, relatively quickly passing to the formation of a stem (Moscow Greenhouse, etc.);
• breakaway, forming a rosette (bush) of large, powerful leaves with different shapes and colors, depending on the variety; does not shoot for a relatively long time (Ruby, etc.);
• head, forming, depending on the variety, heads of cabbage of various shapes, density, sizes and resistance to stemming (Krupnokochny, etc.);
• Romaine salad, combining varieties with an elongated head of cabbage (Parisian green, etc.);
• asparagus, forming plants with a thickened stem, on which elongated narrow leaves are located.

According to the ability to form a head of cabbage, in size, color, quality of leaves and head of cabbage, salads are divided into:

• crispy - the heads of cabbage are relatively dense, the leaves are crispy (with green, greenish-brown or brown outer leaves);
• oily - heads of cabbage are relatively dense, inner leaves are tender, oily, slightly compressed, bleached to light golden or oily yellow shades (with green, greenish-brown or brown outer leaves).

According to the method of cultivation, varieties of head lettuce are also divided into:

• forcing (for greenhouses and hotbeds);
• early ripening spring for growing in the open field in the early stages;
• summer (resistant to stemming);
• winter, for growing in protected ground in a short day and low light.

Thanks to the large variety of varieties and the combination of open and green ground, lettuce can be grown all year round.

77 varieties are included in the State Register of Breeding Achievements of the Russian Federation for 2005.

In recent years, cabbage salads have been of particular interest. They have a delayed transition period to the formation of a flowering stem. Using different sowing dates and varietal characteristics of this type of salad, in the presence of greenhouses, you can get products from early spring to late autumn.

The varieties created in 2005 are of particular interest. They are generally neutral to day length and dim light, allowing for high yields in early spring and late autumn. These include varieties: Azary, Amoriks, Assol, Asteriks, Geyser, Diamond, Severny Blush, Fire, Relay.

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Biological features of culture

Lettuce is a cold-resistant plant. Young plants tolerate a drop in temperature to 1 … 2 ° C and short-term frosts (-6 … -8 ° C). The varieties with highly pigmented anthocyanin leaves are distinguished by the greatest resistance to negative temperatures. Anthocyanin in lettuce leaves, as well as in a number of other crops, plays a protective role under adverse conditions. Cold resistance increases with age.

However, in the phase of head formation, even light frosts can adversely affect the further growth of the plant - they stop setting the head. With prolonged frosts, the head of cabbage that begins to form opens up.

In conditions of sufficient light in spring and summer, plants grow well at 15 … 20 ° C. During the period of head formation, the optimum temperature in the daytime is 14 … 16 ° С, and at night - 8 … 12 ° С. This is especially important to ensure its normal density. Lettuce tolerates heat worse than comparatively low temperatures. In early varieties, air temperatures above 20 ° C cause premature stem formation. In addition, at a high temperature, an excessive decrease in air and soil moisture, lettuce leaves a bitter taste.

Temperature affects the activity of photosynthesis, which determines the rate of growth and development, its quality and the green color of the leaves. Photosynthesis actively proceeds at 20 … 25 ° С. At 0 … 5 ° С photosynthesis is weak, lettuce practically stops growing, at 5 … 8 ° С it forms only a small rosette.

Lettuce is a light-loving plant: in the shade and with thickened sowing, the development of lettuce slows down or loose heads of cabbage form. For the formation of good heads of early maturing varieties, lighting is necessary for 10-12 hours, and for summer, late-ripening varieties - 12-16. Cabbage forms of lettuce have higher light requirements than leafy ones. When shaded, they do not give full-fledged heads of cabbage, which usually happens with thickened crops and late thinning. However, the latter varieties have a remarkable ability to adapt to relatively low light, short day conditions and high humidity.

Early maturity and relatively small area of nutrition are the reason for the high demands of lettuce plants to the conditions of mineral nutrition and water supply. Only on fertile soils and with sufficient moisture can high quality yields be obtained.

The salad is fast growing. With a lack of nitrogen and phosphorus, plants grow poorly, the head of cabbage is formed small with green leaves of dark tones. Among vegetable crops, lettuce ranks third in the removal of nutrients from the soil per crop unit (after radish and asparagus). Moreover, he makes the greatest need for nitrogen-phosphorus nutrition. However, an excess of nitrogen leads to overgrowth of leaves, their delicacy and increased susceptibility to diseases.

The mineral nutrition regimen has a significant effect on the growth of lettuce: a triple increase in nitrogen doses inhibits the growth of young plants and enhances the growth of adults. However, increased nitrogen nutrition in combination with phosphorus has a positive effect on the growth rate of lettuce starting from the early stages of development.

Lettuce is a plant that is sensitive to the reaction of the soil solution. Well-drained fertile soils with a pH of 6.5-7.5 are optimal for it. For growing spring lettuce, the site is prepared in the fall: deep digging is carried out and 10-15 kg of well-decomposed manure, 0.4-0.5 kg of superphosphate, 0.2 kg of potassium fertilizers per 10 m² are introduced. If lettuce is grown as a summer culture, then for deep tillage it is enough to add 0.2-0.3 kg of superphosphate, 0.2 kg of potash fertilizers and 0.15 kg of ammonium nitrate per 10 m². Manure is not applied directly to sowing lettuce. In addition, fresh manure promotes pest growth. Before sowing, the soil must be loosened well, crushed lumps on the surface and leveled.

Head lettuce agricultural technology

To obtain early production, especially head varieties, lettuce is grown by the seedling method using peat-baked pots. Seedling preparation begins with growing seedlings. The seeds are sown in boxes. The embedding depth should not exceed 0.5 cm. When growing a school, before the first true leaf appears, a temperature of 10 … 12 ° C and good lighting conditions are required. This will prevent the seedlings from being pulled out (etiolated). After 12-15 days, the seedlings dive into the pots all the time when wet. Seedlings are usually ready for planting 25-35 days after sowing. Plants at the time of planting should have 4-5 leaves.

The second seeding can be done with a potless crop. However, even with sowing in the first decade of May, the harvest will arrive at a much later date - at the end of June.

In order to get the maximum yield of head lettuce, the planting rate must be observed. Seedlings of lettuce are planted on ridges in three rows at a distance of 30-35 cm. The distance between plants in a row is set depending on the variety: for early ripening varieties - 15-20 cm, for mid-ripening and late-ripening varieties - 20-30 cm. The same distance is made at breakthrough lettuce planted in a seedless way.

Caring for plants consists in weeding and watering during the period of intensive growth of leaves, but before they close in rows, they are fertilized with nitrogen-potassium fertilizers, followed by mandatory loosening. Usually one or two weeding, two loosening, one or two waterings are performed. Regular watering is recommended in dry weather. Good moisture availability will have a beneficial effect on high growth rates and crop quality. During the formation of the head of cabbage, water is less often in order to wet the leaves less.

The readiness for harvesting is determined by the size of the rosette and the density of the head, typical for the given variety. Harvesting is recommended late at night or early in the morning to keep chilled plants fresh for longer. The head lettuce is well preserved at a temperature of 0 … 1 ° C. Packed in plastic bags, it can lie for 3-4 weeks.